Some good pastry makers fold the rolled pastry for the top crust in quarters, cut vents near the center and lift it to the top of the pie. Other pie bakers prefer to cut their own designs (vents) in the pastry and then roll the pastry around the rolling pin and unroll it over the pie. Another school of farm cooks find it easier to avoid stretching the pastry when they cut the vents or prick the top crust after it is adjusted on the pie. Take your choice of methods, but remember to cut vents, plain or decorative, or to prick the top crust to allow steam to escape.